Whether you mount your projector on the ceiling or on a ground-based platform such as a table or shelf, the decision will be the foundation stone of your home theatre setup and everything else will fall into place around it. The size and shape of the room is a starting point in deciding where to put your projector and can influence the type of projector you buy.
The distance of the projector from the screen will determine the size of the projected image and affect brightness. This is called the throw ratio, or projection distance. Careful attention needs be paid to the throw ratio to ensure that a projector will fill a screen from its intended position.
Also, sitting too close for the size of the screen, in particular, will detract from even a top quality projector. So, make sure you’re at the optimum distance to get the maximum quality from your projector. Do your sums first. For help, try the online viewing distance calculator at www.myhometheater.homestead.com or go to www.homecinemacentral.com.au and from the right side menu click Screen Calculator.
If you project your image at an angle from below or above, your image will be wider at the top than the bottom, or vice versa. This wedge shape is called the keystone effect. The ideal positioning is to have the projector centred straight-on to the screen, but this isn’t always possible, so the projector needs to be able to correct this keystone distortion to ensure a correct image.
There are two methods of eliminating the keystone effect: digital keystone correction and lens shift. Of these two, lens shift is the better method as it uses optical adjustment — actually moving the lens — to compensate and keep the image rectangular without degrading image quality. Note though, that you can’t use maximum lens shift in more than one direction at a time.
Digital keystone correction doesn’t move the lens, but aims to compensate for the skew by digitally compressing and distorting the image at the source to make it appear rectangular on screen. This can cause noticeable jaggies along the edge of the corrected image. Of the projectors tested, three had lens shift capability: the Epson, Sanyo and Sony. All the others used digital keystone.
Before you buy a projector, you should probably pause to consider whether it’s the right technology for your environment. Thanks to huge demand and improved mass-production techniques for both mainstream plasma and LCD televisions, projectors have lost their earlier price advantage over flat-panel displays.
On the one hand, even Sharp’s 108-inch monster LCD TV still can’t compete with a home theatre projector at full stretch -- the Sanyo PLVZ2000, for example, can fill a massive 724-inch (diagonal) screen, without the need for a reinforced wall and a team of burly engineers to install it. Conversely, few of us have the hangar-sized lounge room to accommodate such an image, particularly if you want to avoid feeling like you’re stuck in the front row of a cinema.
Ambient light and line-of-sight are also considerations. All displays suffer when used in bright light, but the reflected light of a projection screen is particularly sensitive to this, which limits its effective use to dark environments. Projectors are best mounted on the ceiling to avoid casting shadows when someone gets up to make a cup of tea. Not only that, but you’ll need to consider a separate sound system, as home theatre projectors rarely include speakers (and even then, never enough to fill a large room with quality audio).
The upshot is that, for a home theatre projector to really shine, you need the space for a room with controllable lighting and a dedicated projection surface. Add running costs like lamp replacement to the mix and perhaps a smaller screen size doesn’t sound that bad after all.
Do it in the dark
None of the projectors here will show their best unless the room you use them in is dark — preferably very dark. Any light sources other than the projector will detract from the quality of the projected image. You may want to install ‘blackout’ curtains that you can draw across windows for daytime viewing. Or, you may need a more highly reflective screen to boost image brightness if you can’t make the room completely dark.
This is an important consideration: what to project your high-resolution image onto. Even if you have a completely dark room, don’t be tempted to use your white painted wall for projecting onto if you’re after maximum quality. You need a good quality home theatre screen. Projection screens have special optical coatings that enhance their reflective quality. A plain wall will cut quality in all the important areas: sharpness, highlights, colour balance, contrast, and saturation.
Also, don’t forget the benefit of framing your image properly. A good screen will include the benefit of a non-reflective black border to enhance contrast and provide a clean look to the edges of the picture.
Dedicated projection home screens come in a variety of grades, qualities and even colours — most will be white, but some are a light neutral grey designed to enhance black levels. Screens also come with different ‘gain’ characteristics. Gain is a measure of the amount of light reflected by the screen. A higher gain screen should provide a brighter picture, but not necessarily a better one, to help compensate for more ambient light such as the ‘leakage’ that is often present with daylight viewing. Low gain screens require a completely dark room. A gain of ‘1’ is considered neutral.
Paint your own
If you want a really big screen and you’re a DIY enthusiast you might find it more economical to paint your wall using a reflective acrylic paint specially formulated for projection. There are several brands available and though they’ll set you back a lot more than common house paint, they could give you a megascreen without breaking the bank.
Helpfully, Screen Goo, provides a product selector on its website (www.goosystems.com) to help choose the right type and amount of paint required for a particular screen size and projector model. Other possibilities include Mighty Brighty (www.canohm.com.au) and Paint On Screen (www.paintonscreen.com). Note, however, that we haven’t tested these so we can’t comment on their performance or recommend them.